tinyusb is an open-source (BSD-licensed) USB Host/Device/OTG stack for embedded micro-controller. It is developed using [Test-Driven Development (TDD)](tests/readme.md) approach to eliminate bugs as soon as possible.
tinyusb is designed to be OS-ware and run across OS vendors, thanks to its OS Abstraction Layer (OSAL). However, it can also run without an OS (OSAL will be expanded to be a state machine in this case). Currently the following OS can be run with tinyusb (out of the box).
- LPC11uxx & LPC13uxx cannot able to STALL Control OUT endpoint !!! --> unsupported with data out request may cause host stuck with control transfer forever. (reproduce: enable keyboard + mouse, return error in set report of hid_device)
C is a dangerous language by itself, plus tinyusb make use of goodies features of C99, which saves a tons of code lines (also means save a tons of bugs). However, those features can be misused and pave the way for bugs sneaking into. Therefore, to minimize bugs, the author try to comply with published Coding Standards like:
- [Jet Propulsion Laboratory (JPL) for C](http://lars-lab.jpl.nasa.gov)
Where is possible, standards are followed but it is almost impossible to follow all of these without making some exceptions. I am pretty sure this code base violates more than what are described below, if you can find any, please report it to me or file an issue on github.
### MISRA-C 2004 Exceptions ###
MISRA-C is well respected & a bar for industrial coding standard.
- **Rule 2.2: use only /*** It has long passed the day that C99 comment style // will cause any issues, especially compiler's C99 mode is required to build tinyusb. I think they will eventually drop this rule in upcoming MISRA-C 2012.
- **Rule 8.5: No definitions of objects or function in a header file** function definitions in header files are used to allow 'inlining'
- **Rule 14.7: A function shall have a single point of exit at the end of the function** Unfortunately, following this rule will have a lot of nesting if-else, I prefer to exit as soon as possible with assert style and flatten if-else.
- **Rule 18.4: Unions shall not be used** sorry MISRA, union is required to effectively mapped to MCU's registers
is a small & easy to remember but yet powerful coding guideline. Most (if not all) of the rules here are included in JPL. Because it is very small, all the rules will be listed here, those with *italic* are compliant, **bold** are violated.
8.**`Limit the use of the preprocessor to file inclusion and simple macros`**
Although I prefer inline function, however C macros are far powerful than that. I simply cannot hold myself to use, for example X-Macro technique to simplify code.
If you find my little USB stack is useful, please take some time to file any issues that you encountered. It is not necessary to be a software bug, it can be a question, request, suggestion etc. We can consider each github's issue as a forum's topic. Alternatively, you can buy me a cup of coffee if you happen to be in Hochiminh city.
BSD license for most of the code base, but each file is individually licensed especially those in /vendor folder. Please make sure you understand all the license term for files you use in your project.
